This invention relates to a method for preparing a positive electrode for a non-aqueous electrolyte cell.
Heretofore, the positive electrode for the non-aqueous electrolyte cell has been prepared by first adding a dispersion of polytetrafluoroethylene as a binder to a mixture of a positive electrode-active material and an electrically conductive agent, kneading these components, applying them on a supporting material, and drying it.
However, the use of dispersion of polytetrafluoroethylene as the binder will cause to become a fibrous state at the process where kneading is carried out to obtain a paste mixture, and at this time, masses of the fibrous material are partially produced in the paste mixture. If the paste mixture containing such masses is applied on the corematerial, it will be impossible to obtain the positive electrode in which the active material is homogeneously distributed and the thickness is uniform.
If such an ununiformed positive electrode is used to prepare the cell, the scatter of a discharge capacity will be wide and the prepared cell will thus be poor in quality. For the purpose of overcoming such a drawback, it has been suggested that a semisynthetic water-soluble high polymer such as methyl cellulose or carboxymethyl cellulose is added to the above-mentioned paste, whereby the positive electrode having a uniform thickness can be obtained. However, the positive electrode plate for the non-aqueous electrolyte cell is to be dried at a temperature of about 250.degree. C. before the manufacture of the cell. Therefore, if employed as the positive electrode-active material, the manganese dioxide will react with methyl cellulose or carboxymethyl cellulose, so that the oxidation number of the manganese dioxide will be lowered. When the positive electrode plate which contains the manganese dioxide having such a less oxidation number is used to prepare the non-aqueous electrolyte cell, the discharge capacity of the prepared cell decreases.